What causes the Venturi effect to occur?

The Venturi effect arises from the principle that when a fluid flows through a constricted section of a pipe or around an object, its velocity increases while the pressure decreases. This phenomenon is directly related to the differences in velocity of water flow around the hull of a vessel.

As the hull moves through the water, it alters the flow patterns, creating areas where the water flows faster and areas where it flows slower. The faster-moving water around the hull results in reduced pressure compared to the slower-moving water, demonstrating the essence of the Venturi effect. In the context of a ship's hull, this can influence various factors such as lift and drag, which are crucial for the performance and stability of the vessel in the water.

The other factors mentioned, like changes in the angle of the hull, water temperature, or the size of the ship's hull, do not inherently cause the Venturi effect. They may influence overall vessel performance or hydrodynamics, but they do not directly relate to the core mechanics behind the Venturi effect, which is fundamentally dependent on variations in fluid velocity.